TLDR Dyeing hair can help target and destroy hair follicles selectively.
The study investigated dye diffusion into human skin and hair follicles both in vitro and in vivo. Results demonstrated that dyeing could enhance the absorption coefficient of hair follicle tissue components, making it a potential method for selective photodestruction of hair follicles and surrounding tissues. The research also determined the strength and depth of hair follicle dyeing for various dyes.
69 citations,
January 2002 in “Journal of biomedical optics” Dyes can penetrate human skin and hair follicles up to 1.2 mm deep and the sebaceous gland can store dye; Indocyanine Green lotion was made for safe dyeing and monitoring.
34 citations,
July 2010 in “Expert Opinion on Drug Delivery” The document concludes that there is no agreed-upon best method for measuring drug delivery within hair follicles and more research is needed to validate current techniques.
10 citations,
April 2016 in “Research and reports in transdermal drug delivery” Transfollicular drug delivery is promising but needs more research to improve and understand it better.
2 citations,
July 2004 in “Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE” Near-infrared laser therapy with Indocyanine Green dye improves acne by reducing inflammation without side effects.
2 citations,
July 2017 in “IEEE Photonics Journal” The study found that combining SHG and OCT effectively monitors skin wound healing in mice.